This invention relates to an improved adjustable support mechanism for a computer keyboard or the like. Various mechanisms for supporting keyboards associated with computer terminals have been the subject matter of numerous patents. Smeenge in U.S. Pat. No. 4,616,798, entitled Adjustable Support for CRT Keyboard, discloses a mechanism which includes first and second and sets of parallel, equal length, articulating arms that link first and second brackets with a keyboard platform at one end and a sliding plate attached beneath a desktop at the opposite end. The parallel arms are pivotally connected to the platform and bracket plate and move in a vertical plane to maintain the keyboard support platform in a generally horizontal position regardless of the position of the platform relative to the desktop. During storage of the keyboard support platform, the arms articulate or pivot so that the platform is then lowered to a retracted position beneath the level of the desktop. The arms may be locked in a fixed orientation by a threaded handle or lever which precludes pivotal motion of one or more arms.
Other keyboard support constructions are illustrated in U.S. Pat. No. 4,625,657; 4,632,349; 4,706,919; 4,776,284; 4,826,123; and U.S. Pat. No. 4,843,978. Each of these patents employs a parallel arm type mechanism that allows adjustment of the height of the keyboard support. Another keyboard support mechanism is disclosed in McConnell, U.S. Pat. No. 5,037,054, entitled Adjustable Support Mechanism for a Keyboard Platform. U.S. Pat. No. 5,037,054 teaches a keyboard support mechanism that employs non-parallel arms to support the keyboard platform. This mechanism does not necessarily maintain the keyboard platform in a horizontal position as the arms articulate. Thus, when the keyboard platform is stored under a table, the platform is re-oriented to supply greater access to the kneehole of a desk. The arms may be locked in a desired orientation by means of a threaded handle or lever.
The various prior art mechanisms discussed are useful in conjunction with standard desk equipment. They typically require a threaded handle or lever to lock the keyboard support platform at a desired height location. This type of mechanism, if not operated carefully, may not safely lock the keyboard platform in place. Thus, there has developed a need for improved keyboard support mechanisms for storage of a computer keyboard and which permit easy movement of the platform to a desired level. Additionally, another desired characteristic for such mechanisms is providing a stable surface for the keyboard. Further desirable is an improved mechanism which safely and securely locks a keyboard platform in a desired orientation and which permits easy release or unlocking of the platform from a fixed orientation.